通常是maven仓库不对，或者依赖库存在问题。
maven可以使用aliyun的：
buildscript {
repositories {
maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
google()
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.1.2'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
依赖库问题需要检查dependencies里的依赖是否都能加载的到：
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
}
